Just some thoughts going forward. Maples is best repotted right before bud break. I would not repot a maple in this stage. Now aftercare is very important. Put it in full shade and be very focused on watering until mid summer.
On next repotting I would bareroote and work on the nebari. That lump on one side and crossing roots will just get worse by time. The earlier this work is done the better is the end result.
Nice to see you getting started with bonsai.
As indicated before, a little earlier is probably better for extensive rootwork (Or in late summer when the tree is over the peak growth).
Anyway. You could go a lot further with working the roots. By doing it a bit more assertively, you will create a better rootball.